[RTL-ifcvt] Improve conditional select ops on immediates (fix failing x86_64 cmov...

	PR rtl-optimization/67103
	* ifcvt.c (noce_try_store_flag_constants): Move
	x = (-(test != 0) & (b - a)) + a transformation to...
	(noce_try_cmove): ... Here.  Try it if normal conditional
	move fails.

From-SVN: r226853

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 858eede53ff1de864454255cf9faf4dfe71cd674..a677510789e2317fe719a944bc1dc7f678b0b2cb 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2015-08-13  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+       PR rtl-optimization/67103
+       * ifcvt.c (noce_try_store_flag_constants): Move
+       x = (-(test != 0) & (b - a)) + a transformation to...
+       (noce_try_cmove): ... Here.  Try it if normal conditional
+       move fails.
+
 2015-08-13  Robert Suchanek  <robert.suchanek@imgtec.com>
 
        * config/mips/mips.c (mips_rtx_cost_data): Remove costs for W32 and W64

diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
index 1f2964651f8af7a430a3bd565e4d3bec0c542e5a..9b6f6821ce6f0a81269a6e77530a1ce4c9827d8f 100644 (file)
--- a/gcc/ifcvt.c
+++ b/gcc/ifcvt.c
@@ -1239,9 +1239,6 @@ noce_try_store_flag_constants (struct noce_if_info *if_info)
          normalize = -1;
          reversep = true;
        }
-      else if ((if_info->branch_cost >= 2 && STORE_FLAG_VALUE == -1)
-              || if_info->branch_cost >= 3)
-       normalize = -1;
       else
        return FALSE;
 
@@ -1287,18 +1284,10 @@ noce_try_store_flag_constants (struct noce_if_info *if_info)
                                        target, gen_int_mode (ifalse, mode),
                                        if_info->x, 0, OPTAB_WIDEN);
        }
-
-      /* if (test) x = a; else x = b;
-        =>   x = (-(test != 0) & (b - a)) + a;  */
       else
        {
-         target = expand_simple_binop (mode, AND,
-                                       target, gen_int_mode (diff, mode),
-                                       if_info->x, 0, OPTAB_WIDEN);
-         if (target)
-           target = expand_simple_binop (mode, PLUS,
-                                         target, gen_int_mode (ifalse, mode),
-                                         if_info->x, 0, OPTAB_WIDEN);
+         end_sequence ();
+         return FALSE;
        }
 
       if (! target)
@@ -1615,11 +1604,67 @@ noce_try_cmove (struct noce_if_info *if_info)
                                   INSN_LOCATION (if_info->insn_a));
          return TRUE;
        }
-      else
+      /* If both a and b are constants try a last-ditch transformation:
+        if (test) x = a; else x = b;
+        =>   x = (-(test != 0) & (b - a)) + a;
+        Try this only if the target-specific expansion above has failed.
+        The target-specific expander may want to generate sequences that
+        we don't know about, so give them a chance before trying this
+        approach.  */
+      else if (!targetm.have_conditional_execution ()
+               && CONST_INT_P (if_info->a) && CONST_INT_P (if_info->b)
+               && ((if_info->branch_cost >= 2 && STORE_FLAG_VALUE == -1)
+                   || if_info->branch_cost >= 3))
        {
-         end_sequence ();
-         return FALSE;
+         machine_mode mode = GET_MODE (if_info->x);
+         HOST_WIDE_INT ifalse = INTVAL (if_info->a);
+         HOST_WIDE_INT itrue = INTVAL (if_info->b);
+         rtx target = noce_emit_store_flag (if_info, if_info->x, false, -1);
+         if (!target)
+           {
+             end_sequence ();
+             return FALSE;
+           }
+
+         HOST_WIDE_INT diff = (unsigned HOST_WIDE_INT) itrue - ifalse;
+         /* Make sure we can represent the difference
+            between the two values.  */
+         if ((diff > 0)
+             != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
+           {
+             end_sequence ();
+             return FALSE;
+           }
+
+         diff = trunc_int_for_mode (diff, mode);
+         target = expand_simple_binop (mode, AND,
+                                       target, gen_int_mode (diff, mode),
+                                       if_info->x, 0, OPTAB_WIDEN);
+         if (target)
+           target = expand_simple_binop (mode, PLUS,
+                                         target, gen_int_mode (ifalse, mode),
+                                         if_info->x, 0, OPTAB_WIDEN);
+         if (target)
+           {
+             if (target != if_info->x)
+               noce_emit_move_insn (if_info->x, target);
+
+             seq = end_ifcvt_sequence (if_info);
+             if (!seq)
+               return FALSE;
+
+             emit_insn_before_setloc (seq, if_info->jump,
+                                  INSN_LOCATION (if_info->insn_a));
+             return TRUE;
+           }
+         else
+           {
+             end_sequence ();
+             return FALSE;
+           }
        }
+      else
+       end_sequence ();
     }
 
   return FALSE;